Enantiomerically pure alcohols are widely used in fine chemical industries such as pharmaceuticals, pesticides, perfumes, etc., and thus the studies on the various synthesis methods thereof have been increasing recently. The asymmetric hydrogenation of a prochiral ketone is one of the most important methods in preparing an enantiomerically pure alcohol. This method has gained much attention because of high catalytic activity, quick reaction time, good atom economy, simple product separation, simple post-processing, and less side reactions.
Based on the reasons above, numerous chiral ligands have been developed for the asymmetric hydrogenation of prochiral ketones. Among these ligands, the most representative one is BINAP-based ligands invented by Noyori, a Japanese chemist (EP0901997A1), which achieved good selectivity in the asymmetric hydrogenation of various ketone compounds. However, it is not easy to synthesize such ligand, and the costs are relatively high. In addition, the ligand cannot be stably stored. Further, many other chiral ligands have been applied to asymmetric hydrogenation of ketones. For example, Xumu Zhang et al. have mentioned that the asymmetric hydrogenation of ketones is realized by using a complex of a chiral ligand PennPhos with rhodium (Xumu Zhang et al., Highly Enantioselective Hydrogenation of Simple Ketones Catalyzed by a Rh-PennPhos Complex. Angew. Chem., Int. Ed. 1998, 37, 1100-1103). However, the selectivity of such system is not good, and the ligand is hard to be synthesized and has poor stability. In this respect, it is hard to apply this system in industrial productions. In addition, the use of metal rhodium leads to an increase of the costs.